Isolating the pipeline is an action that will need to be carried out by, or under the close supervision of, pipeline specialists with a full understanding of the consequences of those actions. For example:

• It may be better to keep pipelines flowing to prevent their contents overheating
• Shutting down the supply in pipelines could have a major effect on processes and equipment, both downstream and upstream of the incident
• It may be better not to extinguish fires because an unignited gas or vapour cloud may be a greater hazard
• Depressurisation of pipelines can take some considerable time
• The edges of a vapour cloud are more prone to ignition because of the gas and air mix

Refer to the control measure of Isolate utility or fuel supply within the national grid.